This proposal will focus on the development and use of immunologic techniques to monitor for human exposure to aflatoxin-B1 (AFL-B1). Previously developed monoclonal antibodies recognizing AFL-B1 modified DNA will be used to monitor adduct levels in liver and white blood cell DNA. Monoclonal antibodies with two additional specificities will also be developed, one recognizing the major metabolites of aflatoxin found in urine and the other recognizing the adduct of AFL-B1 with human serum albumin. Competitive enzyme linked immunosorbent assays (ELISA) will be used to sensitively detect metabolites and adducts. These assays will be validated in animals treated with radiolabeled AFL-B1. Immunohistochemical techniques will be developed to determine if there is localization of DNA adducts to specific cell types in liver biopsies. Presence of the DNA adducts will be confirmed by fluorescence measurements on DNA isolated from human liver and enriched in adduct immunoaffinity chromatography. Two pilot epidemiologic studies will be carried out to determine whether thee assays can be used to monitor exposure to aflatoxin. In the pilot case control study, liver and white blood cell DNA adducts will be analyzed in hepatocellular cancer patients and controls from Taiwan. An additional set of tissue controls will consist of autopsy liver samples from the United States. For the pilot environmental correlational study, blood and urine samples will be obtained from randomly selected individuals living in six townships in Taiwan with varying levels of age adjusted mortality form hepatocellular carcinoma. White blood cell DNA adducts, albumin adducts and urinary metabolites will be monitored by ELISA. These studies will determine whether the techniques can be used to monitor human exposure to aflatoxin and determine their sensitivity and applicability to larger scale epidemiologic studies.